O'Hanlon, the founder and former CEO of the web development company Spike, retired from the company in 2000 and from 2001-2003 was Creative Director, Global Brand marketing, for the Mazda Motor Corporation in Japan. During the late 1990s, he was a member of the Governor of California's advisory committee on arts and technology, a council member of The Museum of Australia, Canberra, a member of Austrade's Telecommunications Industry Advisory Panel, and part of the advisory board of the Australian edition of The Industry Standard magazine. He was also a founding judge for the Australian Financial Review/Telstra Internet Awards, the Microsoft Asia-Pacific Web King Awards, and the IdN International Design Awards. O'Hanlon has been a keynote or featured speaker at numerous corporate and academic events and conferences and is a recognised photographer, exhibiting at venues in Australia and overseas.
O'Hanlon turned his back on the business world in 2003 to write. His journalism had already appeared in numerous publications - including The New York Times, Variety, The Industry Standard, The Bulletin, Vogue Australia, TheAustralian Financial Review, The Australian,and The Sydney Morning Herald. Since 2000 his essays and fiction have reflected an ongoing battle with mental illness. O'Hanlon has been diagnosed with Bipolar I (Mixed), an acute form of manic depression.